When we did trace chemicals at college the amount of gold in sea water was something we covered, so sludge would be similar I would think. Not economically viable at the time, but can be when the price of precious metals rise.

The lecturer left us with the percentages of things like arsenic, phosgene and cyanide in tobacco smoke. Made the smokers think for at least 30secs. before lighting up.

". These tend to involve the use of powerful chemicals known as leachates that are used by industrial operations to extract metals from rock. While they can be toxic to ecosystems, in the controlled setting of a sewage plant they can be safely used without environmental risk. "

There is always risk and an STW is not a safe place to use them as they are not designed to do this. You could build an extraction plant alongside an STW.

Most large sewage works are now managed as power stations, processing the sludge to generate gas or heat, to generate energy and the ash goes to the construction industry. If someone wants to extract metals from it they can buy it if us. Maybe one day they will.

The Bradford works used to extract lanolin from the sewage and sold it to the cosmetics industry! Had to stop when the mills closed.

In the old days when the larger sewers were 'walked' by gangs to clear debris, the youngest member was given a buckt to go 'fishing' for loose change and jewellery. The finds being used to buy the beers at the end of the shift.

The bridge, in Kirkstall, good independent pub. I'm going soft, they've got a comfortable bar 3m above the water. Houses used to be where the beer garden is, letting the river in was a regular occurrence.

". These tend to involve the use of powerful chemicals known as leachates that are used by industrial operations to extract metals from rock. While they can be toxic to ecosystems, in the controlled setting of a sewage plant they can be safely used without environmental risk. "

There is always risk and an STW is not a safe place to use them as they are not designed to do this. You could build an extraction plant alongside an STW.

Most large sewage works are now managed as power stations, processing the sludge to generate gas or heat, to generate energy and the ash goes to the construction industry. If someone wants to extract metals from it they can buy it if us. Maybe one day they will.

The Bradford works used to extract lanolin from the sewage and sold it to the cosmetics industry! Had to stop when the mills closed.

that is interesting,if one end product of treatment/energy extraction is ash the idea seems to be plausible to use that as ore if the "feed"is sufficiently rich from either industrial activity or domestic in places where precious metals are common.

". These tend to involve the use of powerful chemicals known as leachates that are used by industrial operations to extract metals from rock. While they can be toxic to ecosystems, in the controlled setting of a sewage plant they can be safely used without environmental risk. "

There is always risk and an STW is not a safe place to use them as they are not designed to do this. You could build an extraction plant alongside an STW.

Most large sewage works are now managed as power stations, processing the sludge to generate gas or heat, to generate energy and the ash goes to the construction industry. If someone wants to extract metals from it they can buy it if us. Maybe one day they will.

The Bradford works used to extract lanolin from the sewage and sold it to the cosmetics industry! Had to stop when the mills closed.

that is interesting,if one end product of treatment/energy extraction is ash the idea seems to be plausible to use that as ore if the "feed"is sufficiently rich from either industrial activity or domestic in places where precious metals are common.

circuit boards and components make quite a rich ore but the "easy" way of getting the metals separated from the plastics and minerals starts with burning them which is a very messy process(especially the way it is done third world style in an old wok).iirc the metal refiners who need to work within decent environmental controls have decided it is uneconomic to do it.

i had considered the direct mince and aqua regia route but that has a few issues with the fumes ,the side products,preventing runaway reactions when "randomly"nitrating a mixture of plastics,paper labels etc,waste disposal and the usual handling problems when messing about with nasty chemicals.

to receive the "ore"in a pre ashed form from a plant made for the job seems ideal.